The present disclosure relates to energy management, and more particularly to power consuming device control methods and electrical energy consumption systems. This disclosure finds particular application to energy management of HVAC systems, such as central air conditioning systems for a home or office building.
Many utilities are currently experiencing a shortage of electric generating capacity due to increasing consumer demand for electricity. Currently utilities generally charge a flat rate, but with increasing cost of fuel prices and high energy usage at certain parts of the day, utilities have to buy more energy to supply customers during peak demand. Consequently, utilities are charging higher rates during peak demand. If peak demand can be lowered, then a potential huge cost savings can be achieved and the peak load that the utility has to accommodate is lessened. In order to reduce high peak power demand, many utilities have instituted time of use metering and rates which include higher rates for energy usage during on-peak times and lower rates for energy usage during off-peak times. As a result, consumers are provided with an incentive to use electricity at off-peak times rather than on-peak times.
Presently, to take advantage of the lower cost of electricity during off-peak times, a consumer typically manually operates an HVAC system during the off-peak times. For example, during off-peak times the consumer can decrease the setpoint temperature of the HVAC system and during on-peak times the consumer can increase the setpoint temperature of the HVAC system and/or turn the HVAC system off. This is undesirable because the consumer may not always be present in the home to operate the system during off-peak hours. This is also undesirable because the consumer is required to manually track the current time to determine what hours are off-peak and on-peak.
One proposed third party solution is to provide an energy management system where a controller “switches” the actual energy supply to the HVAC system on and off. However, there is no active control beyond the mere on/off switching. There are also currently different methods used to determine when variable electricity-pricing schemes go into effect. Also, different electrical companies can use different methods of communicating periods of high electrical demand to their consumer, for example phone lines, schedules, and wireless signals sent by the electrical utility company. Other electrical utility companies simply have rate schedules for different times of day. Therefore, there is a need to provide an improved energy management system that can operate an HVAC system during off-peak hours in order to reduce consumer's electric bills and also to reduce the load on generating plants during on-peak hours.